The present invention is directed to techniques and apparatus employed in medical diagnostics and, more particularly, to a device for sampling liquid samples in which the sample is transported in a capillary-active channel from a sampling site to a determination site.
So-called carrier-bound tests (test carriers, test elements, test strips) are often used for the rapid and simple, qualitative or quantitative analytical determination of components of liquid samples e.g., aqueous body fluids such as blood, serum or urine. In these carrier-bound tests the detection reagents are embedded in corresponding layers of a carrier which is brought into contact with the liquid sample. The reaction of the liquid sample and reagents leads to a detectable signal when a target analyte is present e.g., a measurable electrical signal or a colour change which can be evaluated visually or with the aid of an instrument e.g., by reflection photometry.
Carrier-bound tests are frequently constructed as test strips which are essentially composed of an elongate carrier material made of plastic and detection layers as test fields which are mounted thereon. However, test carriers are also known which are designed as small quadratic or rectangular plates.
Recently, test strips have been in particular offered which contain a capillary-active gap (capillary gap) which conveys sample liquid from one end of the test strip (sampling site or sample application site) to the reagent zones which are typically accommodated at a distance of a few centimeters from the sampling site. This for example makes it possible to apply a sample, in particular a blood sample, to a test strip which is located in an evaluation device without exposing the evaluation device to the risk of contamination by the blood sample.
Test elements typically are essentially composed of a carrier, a cover, and an intermediate layer between the carrier and the cover which together form the capillary-active channel. Reagents that are necessary for the detection of the target analyte or target parameter of the blood sample or liquid sample are located in a defined region within the capillary-active channel. Carrier-bound tests typically have a clearly defined and restricted area in which the sample material can be applied in order to fill the capillary channel. This area is typically either at the end or on one or both side edges of the test carrier. Test carriers are also known in which the liquid sample material is dosed from above or below through an opening in the carrier or in the cover. These variants of sample filling at different sites are typically referred to as front dosing, side dosing and top dosing.
In the case of test strips that are intended to be used by untrained persons, for example by diabetics or anti-coagulation patients for so-called home monitoring, front and side dosing variants of sample filling are typically employed due to the simple handling (usually a drop of blood from the fingertip is introduced onto the test strip). In contrast, test strips with a top dosing variant are typical in the professional field (doctor's offices, medical laboratories, etc.) since blood is usually applied in these cases with application devices such as pipettes or capillaries and because front or side dosing is very difficult to achieve with these devices.
There has previously been a lack of carrier-bound tests that can be used equally advantageously in the home monitoring field as well as in the professional field.